METERED-DOSE AEROSOL VALVES

Abstract: A metered-dose dispensing valve suitable for attachment to an aerosol container and of the type possessing a pressure filling valve in which the valve comprises, as a single integral component (30), a rim gasket (32) for sealing the valve to the aerosol container, the sealing flap (34) of the pressure filling valve and an insert (36) which takes up dead volume within the valve.

Description: METERED-DOSE AEROSOL VALVES This invention relates to metered-dose dispensing valves and in particular to valves for dispensing medicament from pressurised aerosol containers. Known metering valves for pressurised dispensing containers usually have a metering chamber within the valve, the metering chamber having seals at its upper and lower end and being filled with a fresh dose of product to be dispensed, immediately after the previous dose has been dispensed. A valve stem slides through the seals and is movable between an inoperative position where the metering chamber is filled with product to be dispensed and an operative position in which the metered-dose of product is dispensed through the valve stem, the valve stem is spring urged into its inoperative position. Some metering valves are equipped with a pressure filling valve which allows the aerosol container to be filled through the dispensing valve. The pressure filling valve generally comprises a one way flap valve on the side of the metering chamber and the aerosol container is filled by moving the valve stem to its operative position and passing the aerosol propellant composition under pressure through the valve stem into the metering chamber and thence through the pressure filling valve into the aerosol container. Many metering valves also possess means to assist in dispensing the entire contents from the container. Such means may comprise a bottle emptier which envelopes the metering chamber defining a capillary pathway for passage of aerosol composition between the bottle emptier and metering chamber. The inlet to the passageway is positioned such that it will be contacted by the last remaining portion of the aerosol composition. Alternatively, the valve may be provided with an insert which occupies any dead volume such that the last remaining portion of the aerosol composition will be positioned in the vicinity of the entrance to the metering chamber. One problem associated with known metering valves is that they comprise many components which require precision manufacture and complex, accurate assembly. There is a desire to reduce the number of components without deleteriously affecting the performance of the valve. According to the present invention there is provided a metered-dose dispensing valve suitable for attachment to an aerosol container and of the type possessing a pressure filling flap characterised in that the valve comprises, as a single integral component, a gasket for sealing the valve to the aerosol container, the sealing flap of the pressure filling valve and an insert which takes up dead volume within the valve. The invention combines three components into one simple component making savings in both component manufacture and assembly time. Furthermore, since the sealing flap and insert are integral to the sealing gasket they are secured against displacement which might otherwise cause failure of the valve. The "dead volume" of a valve is that space occupied by aerosol formulation from which it cannot be dispensed from the valve when the aerosol container is otherwise empty. The dead volume extends around the metering chamber of the valve and between the valve ferrule and/or neck of the aerosol container to the level of the inlet to the metering chamber. The valves of the invention generally comprise: a valve ferrule having a rim and associated gasket for engaging an aerosol container and an aperture therethrough; a metering tank having walls defining an exterior, an internal metering chamber, an inlet orifice, an inlet end, and an outlet end; an elongate valve stem having a filling channel, a filling end, a discharge end, and a discharge orifice; in which the outlet end of the metering tank is in sealing engagement with the valve ferrule, the discharge end of the valve stem passes through the valve ferrule aperture and the outlet end of the metering tank and is in slidable sealing engagement with the valve ferrule; the filling end of the valve stem passes through and is in slidable engagement with the inlet orifice of the metering tank; and the valve stem is movable between an extended closed position in which the filling channel of the valve stem allows open communication, via the inlet orifice, between the interior and the exterior of the metering chamber and the outlet end of the metering tank is closed, and a compressed open position in which the inlet orifice of the metering tank is in sealing engagement with the filling end of the valve stem and the discharge orifice of the valve stem allows open communication between the interior and exterior of the metering chamber; a pressure filling valve comprising an aperture in a wall of the metering chamber sealed with a movable flap; an insert positioned with the valve ferrule and around the movable flap chamber to occupy dead volume of the valve, the insert preferably being shaped to direct aerosol composition towards the inlet orifice of the metering tank; the rim gasket, movable flap and insert being formed as a single integral component. In accordance with one embodiment of the invention a combined gasket, flap and insert component may completely envelope the valve stem extending through the inlet end of the metering chamber, one or more apertures being provided adjacent the inlet of the metering chamber to facilitate passage of contents to the metering chamber. This arrangement reduces potential drug migration problems. The gasket, flap, insert component may be formed of any suitable material which is sufficiently elastic and is not deleteriously affected by the contents of the container. Suitable materials include thermoplastic elastomers and rubbers e.g. as disclosed in W092/11190. The invention will now be described with reference to the accompanying drawings in which: Figure 1 represents a cross-section through a metered-dose dispensing a valve in accordance with the invention. Figure 2 represents a cross-section through a second metered-dose dispensing valve in accordance with the invention and Figure 3 represents a cross-section through a third metered-dose dispensing valve in accordance with the invention. In the drawings like reference numerals refer to like parts. The valve shown in Figure 1 comprises a valve ferrule (2) having an aperture (4) and side portion (6) which is intended to be crimped over the neck of an aerosol container (not shown) . A metering chamber (7) is defined by a wall (8) positioned within the valve ferrule and has an inlet end (10) and an outlet end (12) and a pressure filling port (13) . A valve stem (14) having a filling channel (16) a filling end (18) a discharge end (20) and discharge orifice (22) extends through the inlet (10) and outlet (12) end of the metering chamber (7) and through the aperture (4) of the valve ferrule. The inlet (10) and outlet (12) ends of the metering chamber (8) are provided with seals (24, 26) respectively such that the valve stem is in sliding sealing engagement. A biasing spring (28) is positioned within the metering chamber biasing the valve stem to its inoperative position as shown in Figure 1. In the inoperative position contents of the aerosol container (not shown) are free to enter the metering chamber (7) via the filling channel (16) . If the valve stem (14) is depressed to its operative position, the filling channel (16) moves through the seal (24) at the inlet end (10) of the metering chamber and the inlet end is sealed. The discharge orifice (22) of the valve stem passes through seal (26) into the metering chamber (8) allowing the contents to discharge through the valve stem via the outlet end (22). In accordance with the invention the valve comprises as a single, integral component (30) , a rim gasket (32) for sealing the valve to an aerosol container, a flap or sleeve (34) sealing the pressure filling port (13) and an insert (36) occupying dead space within the valve such that the contents of the container are directed to the inlet (10) of the metering chamber. The component (30) may readily be precision moulded from suitable elastomeric materials. In use the neck of an aerosol container is inserted in the ferrule (2) until the end of the neck abuts the gasket (32) of the component (30) . The side portion (6) is crimped over the neck to secure the valve forming a gas-tight seal by compressing gasket (32) between the ferrule (2) and the neck of the aerosol container. The aerosol container may be pressure filled by depressing the valve stem (14) and introducing the aerosol formulation under pressure through the discharge end (20) . The formulation passes through the valve stem (14) and enters the metering chamber (7) via the discharge orifice (22) . The pressure of the formulation is sufficient to displace the sleeve (34) from the pressure filling port (13) thereby allowing the aerosol formulation to enter the aerosol container. The insert (36) occupies dead volume within the ferrule (2) . In absence of the insert (36) that space would need to be occupied by aerosol formulation which would be wasted since, when the valve is inverted for dispensing, the formulation would be below the level of the inlet end (10) of the metering chamber (11) and could not enter the metering chamber to be dispensed. Generally, the insert occupies at least 50% of the dead volume, preferably at least 75%, more preferably at least 90% of the dead volume. In one embodiment the insert (36) may be shaped as shown in dotted outline (37) to direct the formulation towards the inlet end (10) of the metering chamber when the aerosol container is substantially empty. Figure 2 shows a modification of the valve of Figure 1 in which the component (30) is provided with a portion (38) which envelopes the filling end (18) of the valve stem. Apertures (40) are provided to allow passage of contents of the aerosol container to the inlet (10) of the metering chamber and to allow passage of the composition into the aerosol container via the pressure filling port (13) when the aerosol container is pressure filled. This arrangement reduces potential drug migration problems. Figure 3 shows a valve similar to that of Figure 1 which additionally comprises a channel (50) extending through the component (30) . The purpose of the channel (50) is to provide an escape route to any aerosol formulation which, during the pressure filling operation, may pass between the wall (8) of the metering chamber and the component (30) to the region (52) . Aerosol formulation which has been forced into region (52) passes through channel (50) into the main body of the aerosol container. It will be appreciated the component (30) of the invention may readily be assembled on the valve and when the valve has been crimped on the aerosol container the insert portion and gassing flap of the pressure filling valve are secured against accidental displacement thereby reducing the risk of valve failure.

Claims: CLAIMS 1. A metered-dose dispensing valve suitable for attachment to an aerosol container, said metered-dose dispensing valve comprising, as a single integral component, a gasket for sealing the valve to the aerosol container, a pressure filling flap, and an insert which takes up dead volume within the valve. 2. A metered-dose dispensing valve, comprising: a valve ferrule having a rim and associated rim gasket for engaging an aerosol container and an aperture therethrough; a metering tank having walls defining an exterior, an internal metering chamber, an inlet orifice, an inlet end, and an outlet end; an elongate valve stem having a filling channel, a filling end, a discharge end, and a discharge orifice; wherein the outlet end of the metering tank is in sealing engagement with the valve ferrule, the discharge end of the valve stem passes through the valve ferrule aperture and the outlet end of the metering tank and is in slidable sealing engagement with the valve ferrule; wherein the filling end of the valve stem passes through and is in slidable engagement with the inlet orifice of the metering tank, and wherein the valve stem is movable between an extended closed position wherein the filling channel of the valve stem allows open communication, via the inlet orifice, between the interior and the exterior of the metering chamber, and wherein the outlet end of the metering tank is closed, and a compressed open position wherein the inlet orifice of the metering tank is in sealing engagement with the filling end of the valve stem and the discharge orifice of the valve stem allows open communication between the interior and exterior of the metering chamber; a pressure filling valve comprising an aperture in a wall of the metering chamber sealed with a movable pressure filling flap, and an insert positioned within the valve ferrule and around the metering chamber to occupy dead volume of the valve, the insert being shaped to direct aerosol composition towards the inlet orifice of the metering tank; wherein the rim gasket, movable pressure filling flap and insert are formed as a single integral component. 3. A metered-dose dispensing valve as claimed in Claim 1 or Claim 2 wherein said single integral component comprises a portion enveloping the end of the valve stem emerging from the metering chamber, one or more apertures being extended through said portion to allow passage of material to the inlet of the metering chamber. 4. A metered-dose dispensing valve as claimed in any preceding Claim wherein said single integral component additionally comprises a channel for passage of aerosol formulation extending therethrough to prevent aerosol formulation being trapped between the single integral component and valve ferrule. 5. A metered-dose dispensing valve as claimed in any preceding Claim wherein said insert occupies at least 50% of the dead volume of the valve. 6. A metered-dose dispensing valve as claimed in Claim 5 wherein said insert occupies at least 75% of the dead volume of the valve. 7. A metered-dose dispensing valve as claimed in Claim 5 wherein said insert occupies at least 90% of the dead volume of the valve. 8. An aerosol container equipped with a valve as claimed in any preceding Claim. 9. A single integral component for a metered-dose dispensing valve comprising a gasket for sealing a valve to an aerosol container, a sealing flap for a pressure filling valve and an insert to take up dead volume with the valve.

Inventors: BOLTON PHILIP, WILDE TREVOR JAMES, BOLTON, PHILIP, WILDE, TREVOR, JAMES
Applicants: BOLTON PHILIP, MINNESOTA MINING & MFG, WILDE TREVOR JAMES, BOLTON, PHILIP, MINNESOTA MINING AND MANUFACTURING COMPANY, WILDE, TREVOR, JAMES
Application year: 1994
Main classification: B65D83
IPC codes: B65D83